/drivers/media/video/v4l2-fh.c

  1/*
  2 * v4l2-fh.c
  3 *
  4 * V4L2 file handles.
  5 *
  6 * Copyright (C) 2009--2010 Nokia Corporation.
  7 *
  8 * Contact: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
  9 *
 10 * This program is free software; you can redistribute it and/or
 11 * modify it under the terms of the GNU General Public License
 12 * version 2 as published by the Free Software Foundation.
 13 *
 14 * This program is distributed in the hope that it will be useful, but
 15 * WITHOUT ANY WARRANTY; without even the implied warranty of
 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 17 * General Public License for more details.
 18 *
 19 * You should have received a copy of the GNU General Public License
 20 * along with this program; if not, write to the Free Software
 21 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 22 * 02110-1301 USA
 23 */
 24
 25#include <linux/bitops.h>
 26#include <linux/slab.h>
 27#include <media/v4l2-dev.h>
 28#include <media/v4l2-fh.h>
 29#include <media/v4l2-event.h>
 30#include <media/v4l2-ioctl.h>
 31
 32int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
 33{
 34	fh->vdev = vdev;
 35	INIT_LIST_HEAD(&fh->list);
 36	set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
 37	fh->prio = V4L2_PRIORITY_UNSET;
 38
 39	/*
 40	 * fh->events only needs to be initialized if the driver
 41	 * supports the VIDIOC_SUBSCRIBE_EVENT ioctl.
 42	 */
 43	if (vdev->ioctl_ops && vdev->ioctl_ops->vidioc_subscribe_event)
 44		return v4l2_event_init(fh);
 45
 46	fh->events = NULL;
 47
 48	return 0;
 49}
 50EXPORT_SYMBOL_GPL(v4l2_fh_init);
 51
 52void v4l2_fh_add(struct v4l2_fh *fh)
 53{
 54	unsigned long flags;
 55
 56	if (test_bit(V4L2_FL_USE_FH_PRIO, &fh->vdev->flags))
 57		v4l2_prio_open(fh->vdev->prio, &fh->prio);
 58	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 59	list_add(&fh->list, &fh->vdev->fh_list);
 60	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 61}
 62EXPORT_SYMBOL_GPL(v4l2_fh_add);
 63
 64int v4l2_fh_open(struct file *filp)
 65{
 66	struct video_device *vdev = video_devdata(filp);
 67	struct v4l2_fh *fh = kzalloc(sizeof(*fh), GFP_KERNEL);
 68
 69	filp->private_data = fh;
 70	if (fh == NULL)
 71		return -ENOMEM;
 72	v4l2_fh_init(fh, vdev);
 73	v4l2_fh_add(fh);
 74	return 0;
 75}
 76EXPORT_SYMBOL_GPL(v4l2_fh_open);
 77
 78void v4l2_fh_del(struct v4l2_fh *fh)
 79{
 80	unsigned long flags;
 81
 82	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 83	list_del_init(&fh->list);
 84	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 85	if (test_bit(V4L2_FL_USE_FH_PRIO, &fh->vdev->flags))
 86		v4l2_prio_close(fh->vdev->prio, fh->prio);
 87}
 88EXPORT_SYMBOL_GPL(v4l2_fh_del);
 89
 90void v4l2_fh_exit(struct v4l2_fh *fh)
 91{
 92	if (fh->vdev == NULL)
 93		return;
 94
 95	fh->vdev = NULL;
 96
 97	v4l2_event_free(fh);
 98}
 99EXPORT_SYMBOL_GPL(v4l2_fh_exit);
100
101int v4l2_fh_release(struct file *filp)
102{
103	struct v4l2_fh *fh = filp->private_data;
104
105	if (fh) {
106		v4l2_fh_del(fh);
107		v4l2_fh_exit(fh);
108		kfree(fh);
109	}
110	return 0;
111}
112EXPORT_SYMBOL_GPL(v4l2_fh_release);
113
114int v4l2_fh_is_singular(struct v4l2_fh *fh)
115{
116	unsigned long flags;
117	int is_singular;
118
119	if (fh == NULL || fh->vdev == NULL)
120		return 0;
121	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
122	is_singular = list_is_singular(&fh->list);
123	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
124	return is_singular;
125}
126EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);